Thread wiping device



Feb. l0, 1970 R. .1. Ross THREAD WIPING DEVICE Filed Dec. 2, 1968 2 sheets-snee*L 1 2 2. 24 25 f f/ l' 3o l l zo 3| "`f 39 a2 f as 35 sa 5 5%: l I3 55g. z 56ML?. 1 |4 59 59 le l l5 es 4s se i I8 Tv' 1ljl, k /f' Fig. l

INVENTOR. Roger J. Ross wlTNEss: ms-f www TQRNEY @www Feb. l0, 1970 i R. J. Ross THREAD WIPING DEVICE Filed Deo. 2, 1968 2 Sheets-Sheei INVENTOR. Roger J. Ross BY Z i TORNEY WITNESS:

5M )mfoml United States Patent O 3,494,316 THREAD WIPING DEVICE Roger I. Ross, Dover, NJ., assignor to 'Ihe Singer Company, New York, N.Y., a corporation of New Jersey Filed Dec. 2, 1968, Ser. No. 780,343 Int. Cl. Db 53/00 U.S. Cl. 112-253 5 Claims ABSTRACT 0F THE DISCLOSURE A mechanism on a sewing machine for lengaging and withdrawing a severed sewing machine needle thread-end from the work fabric at the completion of a line of stitches. The thread wiper includes a member for engaging and 'withdrawing the needle thread-end, a rotary solenoid having a crank and associated driving linkage for moving the needle thread engaging member, and an abutment iixed relatively to the linkage against which the crank engages upon its retraction to a position over-center thereby locking the linkage in its deactivated at-rest position.

SUMMARY OF THE INVENTION This invention relates to structure for wiping a severed sewing machine needle thread from the work fabric at the completion of a stitching operation, and temporarily retaining the severed thread-end until the beginning of the succeeding stitching operation.

Generally, it is the object of this invention to provide a needle thread wiper and thread-end holder which will reliably withdraw the severed thread-end from the work fabric in the limited space available, and which will automatically mechanically lock itself in its deactivated at-rest position.

More particularly, it is the object of this invention to provide a needle thread Wiper having a thread-engaging member which is safe and predictably free from being undesirably drawn into the path of needle reciprocation upon thread severing failure, eifectively preventing damage to the sewing needle and/or being damaged thereby.

It will be understood that what is disclosed in the drawings is merely a preferred embodiment of the invention. The gist of the invention lies in the combination of structure and the orientation thereof.

It is recognized that a conventional rotary solenoid may have built-in stop positions or, in effect, a maximum deactivated retractable position and a maximum activated throw position, within which limits lthe solenoid is operable. Should a rotary solenoid so equipped be employed, this invention, nonetheless, lies in the particular orientation of the built-in stop positions relative to the driving linkage, which orientation accommodates an over-center position of the driving linkage.

The over-center position is that critical position beyond which the solenoid actuated crank must retract upon deactivation so as to facilitate a temporary self-imposed locking of the thread wiping assembly in its deactivated state.

'Should the particular structure be incorporated |without the particular orientation disclosed such that the maximum deactivated retractable position would not accommodate the aforementioned over-center position, then upon a failure of the thread trimmer to sever the needle thread, thread, the thread-wiping-element would be undesirably drawn into the path of the reciprocating needle during the successive stitching operation by the unsevered needle thread, which thread the wiping element has seized, thereby subjecting the thread-wiping-element and/or the sewing needle to potential damage upon their mutual collision.

3,494,316 Patented Feb. 10, 1970 raIce With the a-bove and additional objects and advantages in view as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying dra-W- ings of a preferred embodiment in which:

FIG. l represents an elevational view, partly in section, of a portion o-f a sewing machine having the present invention applied thereto.

FIG. 2 represents a perspective view of a sewing machine presser-foot, a thread carrying needle and a portion of the thread-wiping-element in a state of retraction and seizing a severed needle thread-end.

FIG. 3 represents a perspective view similar to FIG. 2 but showing the thread wiper in its extended thread engaging position.

FIG. 4 represents an elevational view with a modification in which a rotary solenoid lwith a crank and connecting rod are illustrated in a position over-center with the crank engaging an abutment xed over-center.

FIG. 5 represents an elevational view of a further modication in which an alternate locking means is illustrated with the connecting rod engaging an extended abutmentshoulder on the thread-wiping-element.

FIG. 6 illustratess the assembled thread-wiping-element.

DETAILED DESCRIPTION OF THE INVENTION The present invention as shown in FIG. 1 is illustrated as embodied on a conventional lockstitch sewing machine, indicated generally at 10, having a frame including a work supporting bed 11, over which is supported a bracket arm (not shown), terminating in a sewing head 12. Supported for endwise reciprocation in the sewing head 12 is a needlebar 13 having at its lower end a conventional needle clamp 14 in which is detachably secured a needle 15. Shiftably supported for vertical movement in the sewing head 12 is a spring depressed presser-bar 16 carrying at its lower end a presser-foot 17. In the bed and cooperating with the needle 15 to form stitches is a conventional loop-taker or rotating hook 18.

lRigidly fastened on the back of the sewing head 12 by means of a pair of screws 20-20, is a support plate 21. Mounted on the support plate 21 by means of a pair of screws 22-22 is a conventional rotary solenoid 23 having an armature 24 which extends through an opening 25 in the support plate 21. Supported on, and driven by, the armature 24 is a crank 30. Connected to the crank 30 by means of a pin 31 is one end of a connecting link 32. The other end of the connecting link 32 is connected to a block 35 by means of a driving stud 36.

Formed in the block 35 is a cylindrical bore accommodating one extremity of a cylindrical rod 38, which extremity is secured in the block 35 by a set screw 39; The other extremity of the cylindrical rod 38 has an axially formed slot 40, shown in FIG. 6, within which a threadwiping spring-iinger 41 is secured by means of a pin 42. The thread-wiping spring-finger is preferably made of flat resilient material such as spring steel having its lower free extremity formed with a .point 43 and at one side a barb 44.

Mounted in sewing head 12 is a bushing 50, which bushing Shiftably supports a presser-bar 16. Fastened to the bushing 50 is a mounting block 51 formed with a split aperture 52, which aperture accommodates the presser-bar bushing 50. The mounting block 51 is deta3chably secured to the bushing 50 by a clamping screw 5 The mounting block 5.1 is formed with an inclined semi-cylindrical groove 55, which groove 55 is complementa] to an enclosed semi-cylindrical groove 56 formed in the clamping bar 58. The clamping bar 58 may be secured to the mounting block 51 by means of the screw 59.

Upon securing the clamping bar 58 to the mounting block 51, the opposing complemental semi-cylindrical grooves 55 and 56 from a rigid supporting brace for the thread-wiping guide tube 62 having a bend at 63 so as to direct the thread-wiping spring-finger 41, being shiftably supported therein, toward the reciprocating needle 15.

It will be understood that the crank 30 and connecting link 32 have a mutually overlapping position as shown in FIG. 4, which position will hereinafter be referred to as an over-center position.

The rotary solenoid 23 is fixed relative to frame 10 on the support plate 21 such that the limits of deactivated retraction and maximum activated throw of the rotary solenoid or, in effect, the solenoid range of operability, include the aforementioned over-center position of the crank 30 relative to the connecting link 32.

Reference may be made to my pending U.S. application No. 648,385, tiled June 23, 1967, for a complete disclosure of the electrical control system which may be incorporated with the present invention for selectively exciting the thread-wiping mechanism described herein.

Reference may also be made to my said pending U.S. application and also to my U.S. Patent No. 3,386,402 for a complete disclosure of the thread trimming device which cooperates in combination with the thread-wiping mechanism herein, which trimming device selectively severs the needle thread 65 at the end of a line of stitches immediately prior to the activation of the thread-wiping rotary solenoid 23.

Briefly, however, FIG. 1 includes an illustration of a conventional sewing machine rotating hook 18 formed with a needle thread seizing beak S1 for seizing and carrying a loop of needle thread 65 about a bobbin thread (not shown), the bobbin thread issuing from a bobbin case 83. The thread trimming device includes a thread-catching-element 84 selectively shiftable for engaging and seizing both the bobbin thread and needle thread 65 and for drawing these threads into the path of a thread cutting knife 86.

It sometimes happens during the operation of mutually cooperating mechanisms acting in sequentially timed stages, that one of the elements in the combination suffers mechanical diiculty and functionally fails, which failure may present a detrimental environment to those members which continue to function. The particular problem overcome by the present invention relates to just such a case.

The structure disclosed herein greatly depends on the functional stability of the threadtrimming mechanism. Should the thread-trimming mechanism fail to sever the needle thread at the end of a line of stitches, then during the successive stitching operation the thread-wiping spring-finger 41 may be subsequently pulled into the path of the reciprocating needle by the unsevered needle thread, which thread the spring-finger 41 has timely seized. This may occur in the absence of an accommodation of the over-center position by the operable range of the solenoid, thereby subjecting the needle and threadwiping spring-finger 4.1 to potential damage upon their mutual collision.

With the rotary solenoid 23 aixed relative to frame 10 such that the solenoid range of operability includes the over-center position of the crank 30 relative to the connecting link 32, the collision and potential damage as discussed and described above would be prevented. Upon the deactivated retraction of the crank 30 into a position over-center, a force exerted downwardly against the spring-finger 41 tending to urge the spring-finger 41 into the path of needle reciprocation, as, for instance would be exerted by an unsevered needle thread after having been timely seized by the spring-finger 417 would merely urge the crank and the solenoid armature internal structure 'into a state of further retraction against the solenoid built-in at-rest structure, which structure would effectively prevent the spring-finger 41 from being undesirably drawn into the path of needle reciprocation. With the arrangement of this invention, the thread if not severed by the thread-trimming mechanism, upon initiation of a subsequent sewing operation would be broken before it would draw the spring-finger 41 toward the needle path.

FIG. 4 illustrates a modified form of construction in which an abutment stop lug is carried by, or formed as a part of, the support plate 21. The stop lug is positioned for cooperative engagement with the crank 3() in a position of the crank slightly beyond the aforementioned over-center position. The stop lug 90 may replace the built-in stops with which the rotary solenoids may be equipped. The stop lug 90 may also be used together with, and in addition to, a rotary solenoid equipped with built-in stops in which case the stop lug 90 provides for a more selectively predeterminable and more structurally rigid locking means.

A further modification is illustrated in FIG. 5 in which a stop abutment is carried by, or formed as a part of, the block 351. Preferably, the block 351 in this modication is formed with a shoulder 101 extended in the direction of the cylindrical rod 38 so as to position the abutment 100 for cooperative engagement with the connecting link 32 in a position over-center upon the deactivated retraction of crank 30.

Having thus set forth the nature of this invention, what I claim herein is:

1. A needle-thread-wiping device adapted for use on a sewing ymachine having a frame, a thread-carrying needle supported in said frame for reciprocation in an endwise path, and a thread-trimming mechanism associated with said sewing machine including a threadsevering element, said thread-wiping device comprising in combination:

(a) a guide means carri-ed by said fra-me and having a termination remote from said needle path;

(b) a thread-wiping element shiftably supported in said guide means and having a portion movable beyond the termination of said guide means;

(c) a needle-thread-engaging means carried on one extremity of said portion of said thread-wiping element;

(d) a linkage means including a crank and a link connecting said crank with said thread-wiping element, said linkage means having an over-center position defined by a mutually overlapping relationship of said link with said crank;

(e) an energizing means supported relatively to said frame and operatively connected to said linkage means for selectively driving and retracting said linkage means;

(f) an abutment engageable with said linkage means,

yand

(g) means for fixing said abutment relatively to said linkage means for engagement with said linkage means in said over-center position u-pon the deactivated retraction of said linkage means, thereby preventing said thread-engaging extremity on said thread-wiping element from being undesirably drawn into the path of reciprocation `of said needle upon failure of said thread-severing element on said thread-trimming mechanism to sever said thread.

2. A needle-thread-wi'ping device as set forth in claim 1 in which said energizing means is a rotary solenoid.

3. A needle thread-wiping device as set forth in claim 2 including support -means for said rotary solenoid, said abutment being secured to said support means.

4. A needle-thread-wiping device as set forth in claim 2 wherein said thread-wiping element includes a second extremity to which said linkage means is connected, said abutment being formed as a portion of said second extremity.

5. A needle-threadwiping device adapted for use on a sewing machine having a frame, a thread-carrying needle supported in said frame for reciprocation in an endwise path, said thread-wiping device comprising in combination:

(a) a guide means carried by said frame;

(b) a thread-wiping element shiftably supported in said guide means;

(c) a needle-thread-engaging means carried on one extremity of said thread-wiping element;

(d) a linkage means including a crank and a link connecting said crank with said thread-wiping element, said linkage means having an over-center position defined by a mutually overlapping relationship of said link with said crank;

(e) an energizing means operatively connected to said linkage means for selectively driving and retracting said linkage means, said energizing means References Cited UNITED STATES PATENTS 1,352,514 9/1920 Hill i12-252 1,358,847 11/1920 Hill 112-252 1,255,489 2/1918 Triem 112-252 1,332,683 3/1920 Ray 112-252 3,413,944 12/1968 Spinrad et al 112-252 MERVIN STEIN, Primary Examiner GEORGE H. KRIZMANICH, Assistant Examiner 

